Biology subject test (4)

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MCAT Subject Tests Dear Future Doctor, The following Subject Test and explanations contains questions not in test format and should be used to practice and to assess your mastery of the foundation content necessary for success on the MCAT Simply memorizing facts is not sufficient to achieve high scores; however, an incomplete understanding of basic science knowledge will limit your ability to think critically Think of building your content knowledge as learning the vocabulary and practicing MCAT-like questions as actually speaking All rights are reserved pursuant to the copyright laws and the contract clause in your enrollment agreement and as printed below Misdemeanor and felony infractions can severely limit your ability to be accepted to a medical program and a conviction can result in the removal of a medical license We offer this material for your practice in your own home as a courtesy and privilege Practice today so that you can perform on test day; this material was designed to give you every advantage on the MCAT and we wish you the best of luck in your preparation Sincerely, Albert Chen Executive Director, Pre-Health Research and Development Kaplan Test Prep © 2003 Kaplan, Inc All rights reserved No part of this book may be reproduced in any form, by Photostat, microfilm, xerography or any other means, or incorporated into any information retrieval system, electronic or mechanical without the written permission of Kaplan, Inc This book may not be duplicated, distributed or resold, pursuant to the terms of your Kaplan Enrollment Agreement _ B I O L O G Y S U B J E C T T E S T Biology Subject Test Which of the following produces bile? A B C D E A B C D E spleen liver bone marrow heart veins The pacemaker is the SA node The SA node is capable of autonomous firing The vagus nerve can slow the heart rate Systolic pressure is lower than diastolic pressure Both ventricles contract simultaneously In a reflex arc A the sensory neuron synapses directly with the motor neuron B sensory and motor neurons can synapse outside of the spinal cord C sensory neurons synapse in the brain D the motor response occurs without synaptic delay E a minimum of three neurons must participate Constriction of the pupil Decreased heart rate Increased gastric secretion Reduction of adrenaline secretion Increased respiration Skeletal muscle has all of the following except A B C D E multinucleated cells sarcoplasmic reticulum intercellular conductivity of action potentials individual innervations of each muscle fiber a regular array of molecular components Epinephrine A B C D E Which statement about the heart is NOT true? The sympathetic nervous system causes which of the following? A B C D E Small intestine Large intestine Gall bladder Liver Pancreas In the adult man, red blood cells are produced in the A B C D E is synthesized by the adrenal cortex is a steroid hormone is released during parasympathetic stimulation is released by the adrenal medulla causes bronchial constriction when released into the bloodstream An action potential spike is due to A B C D E K+ increased permeability to increased permeability to Na+ decreased permeability to Ca2+ membrane hyperpolarization increased permeability to Cl– The liver performs all of the following functions except A B C D E removal of bacteria from the bloodstream removal of bilirubin from the bloodstream synthesis of bile storage of bile synthesis of angiotensinogen 10 Pancreatic exocrine secretions contain all of the following EXCEPT A B C D E proteases lipases amylases glucagon bicarbonate ions KAPLAN B I O L O G Y S U B J E C T T E S T 11 Acetylcholine A B C D is secreted by the adrenal glands is the initial substrate in glycolysis is an intermediate in the citric acid cycle and norepinephrine act as transmitters across synapses E inhibits action potential transmission 12 A rectifier is an electrical device that allows current to flow only in one direction In human physiology, an analogous device is the A B C D E axon dendrite synapse Schwann's sheath spinal nerve 13 What is the probability of a tall child with blue eyes being born to a heterozygous tall, heterozygous browneyed mother and a homozygous tall, homozygous blueeyed father, if tall height, and brown eye color are dominant? (NOTE: the genes for eye color and height are unlinked.) A B C D E 1/4 1/2 3/4 1/8 None of the above 14 If a gallstone blocked the duct leading from the gallbladder, which of the following would be less easily digested? A B C D E Amino acids Proteins Fats Starch Glycogen 15 The cartilaginous structure that prevents food from going down the trachea is the A B C D E 16 In the speculation concerning the origins of life, one theory states that purines, pyrimidines, sugars, and phosphates combined to form A B C D E nucleotides nucleosides carbohydrates fats proteins 17 Anaerobic respiration is less efficient than aerobic respiration because A oxaloacetic acid serves as the final hydrogen acceptor B it occurs in water C it requires a greater expenditure of cell energy D it requires a longer time for ATP production E glucose molecules are incompletely oxidized 18 Muscle contraction depends on A myosin and actin fibers simultaneously contracting B myosin contraction only C actin contraction only D myosin and actin sliding over each other E myosin expanding while actin contracts 19 In humans, most of digestion occurs in the A B C D E mouth stomach liver small intestine pancreas 20 Which of the following is not a function of the human liver? A B C D E Breakdown of amino acids to urea Regulation of blood sugar levels Detoxification of poisons Storage of glycogen Manufacture of red blood cells in the adult glottis epiglottis tongue larynx esophageal sphincter KAPLAN _ B I O L O G Y S U B J E C T T E S T 21 If the pancreatic ducts of a human are tied off, which of the following is mostly likely to occur in several hours? I Diabetic crisis II Acromegaly III Impaired digestion A B C D E I only II only III only I and II II and III 22 Active transport is best defined as A diffusion of soluble substances across a membrane from a region of high concentration to low concentration B osmosis of water across a semi-permeable membrane involving the hydrolysis of polypeptides C the movement of materials across a semipermeable membrane against an electrochemical gradient D the movement of materials across a semipermeable membrane with an electrochemical gradient E the movement of substances across a membrane in accordance with the Donnan equilibrium 23 Which of the following hormones raises the concentration of blood calcium? A B C D E Glucagon Calcitonin Parathyroid hormone Aldosterone Anti-diuretic hormone 24 Which of the following is not a necessary condition for the Hardy-Weinberg equilibrium? A B C D Random mating Large gene pool Random emigration and immigration Forward mutation rate equals backward mutation rate E No inbreeding 25 Temperature regulation is a function of the A B C D E medulla pons cerebrum pineal gland hypothalamus 26 Which of the following stimulates the conversion of glycogen to glucose? A B C D E Insulin Parathyroid hormone Pepsin Glucagon Calcitonin 27 Which of the following events occurs first? A B C D E Rupture of the Graafian follicle Secretion of estrogen Corpus luteum formation Progesterone release Decrease in FSH release by pituitary 28 Water absorption occurs primarily in the A B C D E duodenum jejunum stomach large intestine mouth 29 Which of the following glands produces both exocrine and endocrine secretions? A B C D E Parathyroid Adrenal Pituitary Parotid Pancreas 30 Continuous muscle contraction causes a buildup of lactic acid because A it is a breakdown product of ADP B it is a degredation product of phosphocreatine C it is a metabolic end-product of anaerobic metabolism D it is a breakdown product of fatty acid degradation E actomyosin contraction releases cross-links of lactate 31 All viruses A B C D E carry DNA carry RNA lack protein have chromosomes cannot reproduce outside of cells KAPLAN B I O L O G Y S U B J E C T T E S T 32 Bile is a (an) A B C D E hormone enzyme protein emulsifying agent protease 33 Which of the following directly supply the energy for muscle contraction? A B C D E Lactic acid Lactose ADP ATP and phosphocreatine cAMP and ATP 34 Hyperthyroidism is always associated with A B C D E low blood pressure severely diminished mental activity high metabolic rate low body temperature decreased heart rate 35 Carbon monoxide, when inhaled, may be lethal because A of its irritation of the pleura B of its preferential replacement of oxygen in hemoglobin C it forms insoluble complexes in the bloodstream D it poisons the cytochrome system E it directly inhibits the sodium pump 38 Which stage of embryonic development consists of a hollow ball of cells surrounding a fluid filled center? A B C D E Zygote Morula Blastula 2-Layer gastrula 3-Layer gastrula 39 Which of the following aspects of cellular respiration is correctly paired with the location in the cell where it occurs? A Electron transport chain-inner mitochondrial membrane B Glycolysis-inner mitochondrial membrane C Krebs cycle-cytoplasm D Fatty acid degradation-lysosomes E ATP synthesis-outer mitochondrial membrane 40 Chemical X is found to denature all enzymes in the synaptic cleft What are the effects of chemical X on acetylcholine (ACh)? A ACh is not released from the presynaptic membrane B ACh does not bind to the postsynaptic membrane C ACh is degraded before it acts on the postsynaptic membrane D ACh is not inactivated in the synaptic cleft E None of the above STOP! END OF TEST 36 In which of the following would you find cristae? A B C D E Endoplasmic reticulum Mitochondria Nucleus Nucleolus Ribosomes 37 Which of the following is NOT a metabolic waste product? A B C D E CO2 lactate H2O pyruvate ammonia KAPLAN _ B I O L O G Y S U B J E C T T E S T THE ANSWER KEY AND EXPLANATIONS BEGIN ON THE FOLLOWING PAGE KAPLAN B I O L O G Y S U B J E C T T E S T BIOLOGY SUBJECT TEST ANSWER KEY D D 17 E 25 E 33 D C 10 D 18 D 26 D 34 C E 11 D 19 D 27 B 35 B D 12 C 20 E 28 D 36 B B 13 B 21 C 29 E 37 D D 14 C 22 C 30 C 38 C E 15 B 23 C 31 E 39 A C 16 A 24 C 32 D 40 D KAPLAN _ B I O L O G Y S U B J E C T T E S T EXPLANATIONS D The liver produces bile Bile contains no enzymes; it emulsifies fats, breaking down large globules into small droplets The small intestine, choice A, is where chemical digestion is completed and nutrients absorbed The large intestine, choice B, functions in the absorption of salts and water The gall bladder, choice C, stores the bile prior to its release in the small intestine The pancreas, choice E, produces digestive enzymes (e.g amylase, trypsin, and lipase) and hormones (e.g insulin and glucagon) C Red blood cells are produced in the bone marrow In the fetus, they are produced in the liver Answer choice A is incorrect because the spleen stores a volume of blood and filters it but does not produce it Answer choice B is incorrect because the liver removes foreign material and detoxifies chemicals in the blood Answer choice D is incorrect because the heart provides the pressure that enables the blood to travel throughout the body Answer choice E is incorrect because the veins deliver blood to the heart E The sympathetic nervous system is known as the "fight or flight" response Stimulation of this branch of the autonomic nervous system is characterized by an increase in heart rate, dilation of the pupils, an increase in respiration and bronchial dilation, and more blood to the skeletal muscles and away from the digestive organs Also, an increase in the amount of adrenaline secretion occurs Answer choices A–D are all characteristics of the antagonistic branch of the autonomic nervous system, the parasympathetic nervous system, known as the "rest and digest" response D Epinephrine, also known as adrenaline, is released by the adrenal medulla Answer choice C is incorrect because this release is stimulated by the sympathetic nervous system Answer choice B is incorrect because epinephrine is a peptide hormone; steroid hormones are produced by the adrenal cortex Answer choice E is incorrect because epinephrine causes bronchial dilation B An action potential spike refers to the depolarization of the axon First, the axon becomes more permeable to Na+ ions from the outside through the opening of sodium channels In rushes sodium, and then the potassium channels open and K+ rushes out of the axon Afterwards, the cell is returned to normal through the action of the Na+/K+ pump Answer choices C and E are incorrect because Ca2+ and Cl– ions are not associated with depolarization and answer choice D is incorrect because hyperpolarization actually makes an axon less likely to trigger an action potential D The heartbeat is initiated by the sino-atrial node located in the wall of the right atrium, and travels through the atria It is regulated but not controlled by the accelerator nerve (sympathetic) and the vagus nerve (parasympathetic) It is then picked up by the AV node, which signals the bundle of His (AV bundle), which transports the contraction through the KAPLAN B I O L O G Y S U B J E C T T E S T ventricles via the Purkinje fibers While the AV node does have contractile ability and controls the contraction of the ventricles, it does not control the contraction of the entire heart and is not as regular as the signal from the SA node The SA node is located in the wall of the right atrium and is not functionally dependent upon nervous stimulation as this tissue initiates the heartbeat, although it can be modified by the nervous system The delay between the contraction of the atria and the ventricles allows for the filling of the ventricles with the blood from the atria The systolic pressure is actually higher than the diastolic pressure as the systolic pressure is the pressure of the ventricular contraction while the diastolic pressure is the pressure between contractions E A reflex arc is a stimulus coupled to a rapid motor response, and is meant for quickness or protection Examples of this are blinking or recoiling away from a hot stove An example of a reflex arc would begin with you touching a hot pot on a stove, which would stimulate a sensory nerve The sensory nerve directs a signal towards the CNS, and synapses with an interneuron in the spinal cord The interneuron (which is entirely within the spinal cord) synapses with a motor neuron, which delivers the response signal to your arm and hand, causing you to involuntarily drop the pot and move your arm away The process requires no input from the brain Answer choice C is incorrect because although some sensory neurons due synapse in the brain, those that are involved in simple reflex arc not Answer choice D is incorrect because there is a very brief delay that occurs at the two synaptic junctions (it takes time for the neurotransmitters to diffuse) C Skeletal muscle has multinucleated fibers with a regular array of actin and myosin filaments These filaments slide along each other and shorten during contraction This process requires ATP Each muscle cell/fiber is innervated by a branch of the nerve innervating this muscle The axon releases an action potential to each muscle fiber This action potential cannot pass from one muscle fiber to another When this action potential reaches the muscle fiber, it causes the release of Ca2+ from the sarcoplasmic reticulum to initiate the sliding of the actin and myosin filaments D The liver is a biochemical factory that stores sugar as glycogen in response to insulin levels; breaks down glycogen to glucose due to signals from glucagon and epinephrine; converts excess amino acids to glucose, fats, and ammonia; converts ammonia to urea for excretion; removes bacteria and bilirubin (which is utilized in the formation of bile salts) from the bloodstream; synthesizes angiotensinogen; and produces bile, which emulsifies fats Therefore, only answer choice D is not listed as a function of the liver but is rather a function of the gall bladder The liver produces the bile while the gall bladder stores it until it is needed 10 D As an exocrine gland, the pancreas secretes proteases, lipases, and amylases, which aid in the digestion of food, and bicarbonate ions which buffer the pH of the chyme coming from the stomach Glucagon is an endocrine secretion of the pancreas in response to a low blood glucose level It causes an increase in the levels of glucose through the degradation of glycogen, and decreases the uptake by muscles 11 D Acetylcholine is a neurotransmitter found in neuromuscular junctions and synapses Norepinephrine, dopamine, and serotonin are also neurotransmitters found in these locations They are chemical messengers released as action potential reaches the end of the axons After crossing the synaptic cleft, they cause the depolarization of the adjacent cell membrane Answer choices A, B, and C are incorrect because acetylcholine isn't secreted by the adrenal glands and is not KAPLAN _ B I O L O G Y S U B J E C T T E S T involved in glycolysis or the citric acid cycle Answer choice E is incorrect because it does not inhibit an action potential, rather it causes an action potential 12 C The synapse is a small space between an axon and dendrite of two neurons After stimulation, the axon will release a neurotransmitter across this cleft, which will diffuse and bind receptors on the dendrite of the next neuron The neurotransmitter can only be released by the axon and can only be received by the dendrite and is therefore similar to a rectifier Answer choice A is incorrect because the axon is only the section of the neuron away from the cell body while answer choice B is incorrect because the dendrite is the section of the neuron going toward the cell body Answer choice D is incorrect because Schwann cells are insulating cells of the neurons Answer choice E is incorrect because a spinal nerve is a bundle of nerves where they enter and exit the spinal cord 13 B Let’s first define the alleles in this problem Let T equal tall height and t equal short height Now let’s define B as brown eye color, and b as blue eye color The father is described as homozygous tall and homozygous blue-eyed, so we know his genotype is TTbb The mother is described as heterozygous tall and heterozygous brown-eyed, so her genotype is TtBb This question asks you to determine the probability that these parents could produce a tall child with blue eyes (T_bb) Remember, the genes for height and eye color are unlinked Now, the father can only contribute the T and b alleles, so all of his gametes will have both the T and b alleles On the other hand, the mother can contribute either T or t and either B or b, so her gametes are the following, all in equal amounts: TB, tB, Tb, or tb Thus, the possible genotypes of the offspring are: TTBb, TTbb, TtBb, Ttbb Half the offspring are tall and brown eyed, and the other half are tall and blue-eyed Therefore, the probability of a tall child with blue eyes is 1/2 (one out of two), or choice B A shorter method involves calculating phenotype ratios for height and eye-color seperately and then combining them The mating of TT x Tt produces 100% tall The mating of Bb x Bb produces one half blue and one half brown Multiplying tall times one half blue gives us one half tall blue, or choice B 14 C Bile is formed in the liver and released by the gall bladder, and emulsifies fats to increase the surface area of the fat molecules so that lipases can break them down Therefore, without bile, fats would be more difficult to digest 15 B The cartilaginous structure that prevents food from going down the trachea is known as the epiglottis This structure closes off the respiratory tract and covers the glottis, which is the opening at the top of the trachea Answer choice C is incorrect because the tongue is a muscle, not cartilage, and does not close off the trachea Answer choice D is incorrect because the larynx is also known as the voice box, and is located below the glottis Answer choice E is incorrect because the esophageal sphincter is also known as the cardiac sphincter, and separates the esophagus from the stomach 16 A Nucleotides are made up of a nitrogenous base, guanine, uracil, adenine, cytosine, or thymine; a sugar, either ribose or deoxyribose; and a phosphate group Adenine and guanine are purines while thymine, cytosine, and uracil are pyrimidines Answer choice B is incorrect because a nucleoside does not contain the phosphate group, just the nitrogenous base and the sugar Answer choice C is incorrect because carbohydrates are only sugars, while answer choice D is incorrect because fats are glycerols and three fatty acids Answer choice E is incorrect because proteins are only linked amino acids and not contain anything found in a nucleotide KAPLAN B I O L O G Y S U B J E C T T E S T 17 E Cellular respiration is the most efficient catabolic pathway used by organisms to harvest the energy stored in glucose Whereas glycolysis yields only two ATP per molecule of glucose, cellular respiration can yield 36–38 ATP Cellular respiration is an aerobic process; oxygen acts as the final acceptor of electrons that are passed from carrier to carrier during the final stage of glucose oxidation The metabolic reactions of cell respiration occur in the eukaryotic mitochondrion and are catalyzed by reaction-specific enzymes 18 D Muscle contraction occurs when two types of muscle proteins slide past each other, thus creating a contraction These two types of muscle fibers or muscle proteins are known as actin and myosin fibers Myosin fibers are thick fibers, and actin fibers are thin fibers They slide past each other as ATPs are used as an energy source Neither one of the fibers shrinks in size The muscle cell itself will shrink in size because the fibers slide past each other, thereby causing a decrease in the size of the muscle cell, and therefore a contraction of the muscle Likewise, neither actin nor myosin fibers can expand So therefore choices A, B, C, and E are all incorrect 19 D Most chemical digestion within human beings occurs in the small intestine Within the small intestine, almost all protein digestion, all disaccharide digestion, most starch digestion, all fat or lipid digestion, and all absorption of food occurs There is, previous to the small intestine, a small amount of starch digested in the mouth by salivary amylase into the disaccharide maltose There is also within the stomach a small amount of protein digestion, in which the stomach enzyme pepsin splits proteins into smaller chains of amino acids known as peptides However, the digestion occurring before the small intestine is not very significant, and almost the entire digestive process occurs within the small intestine Answer choice C is incorrect because the liver is not part of the alimentary canal; that is, food does not pass through the liver The liver does produce bile, an emulsifying agent, which helps increase the surface area of fats and mixes them within the watery enzyme environment of the small intestine Choice E is incorrect for the same reason The pancreas does produce a number of digestive enzymes, including the proteases trypsin and chymotrypsin, and the fat-digesting enzyme lipase, as well as pancreatic amylase The enzymes, however, operate within the small intestine, not the pancreas itself 20 E The liver is a multi-function organ, necessary for the maintenance of life in humans The liver does form urea from the metabolism of excess amino acids Amino groups are removed from the amino acids, and eventually these amino acids can be changed into other molecules such as glucose, glycogen, and fats The amino groups, which are removed from the amino acids, are combined with CO2 through a series of reactions to form the moderately toxic waste product urea The liver also regulates blood sugar level by removing glucose from the blood when the blood glucose is high, storing it as glycogen, likewise breaking down glycogen and putting glucose back into the blood when blood glucose is low The liver can detoxify many compounds, including alcohol and other drugs Likewise, it can take apart many pharmaceutical products and chemicals, and readies them for excretion by the kidneys The liver does not manufacture red blood cells in the adult, although it is a source of red blood cells in the developing fetus Red blood cells in the adult are formed primarily in the red bone marrow 21 C Pancreatic ducts lead from the pancreas to the duodenum They carry pancreatic enzymes, including pancreatic amylase, lipase, and some proteases, such as trypsin and chymotrypsin, from the pancreas to the duodenum The pancreatic duct also delivers bicarbonate, which is contained in the pancreatic secretions, which helps to neutralize acidic stomach contents as they enter the duodenum The hormones produced by the pancreas not pass through the pancreatic ducts Hormones are secreted directly into the bloodstream The pancreas is a dual organ, in that it produces both enzymes and hormones So a diabetic crisis will not occur, as a tying off of the pancreatic ducts will not affect the production of pancreatic hormones insulin and glucagon Choice II is also incorrect; acromegaly is a result of excessive 10 _ KAPLAN _ B I O L O G Y S U B J E C T T E S T secretion of growth hormone in an adult It causes excessive bone growth of some facial bones, and the result is a characteristic distorted facial appearance There is no connection between the growth hormone, which is secreted by the anterior pituitary, and the tying off of the pancreatic duct, so only choice III will occur 22 C Active transport is defined as the use of energy to move a substance across a membrane against a concentration gradient 23 C Parathyroid hormone is secreted by the parathyroid gland Its function is to increase blood calcium through removal of calcium from bones and other calcium-containing tissues The removal of calcium from bones is primarily done by osteoclasts, which are bone-absorbing cells The antagonistic hormone to parathyroid hormone, which reduces blood calcium by depositing it into bone and other calcium-containing tissue, is calcitonin, choice B, secreted by the thyroid gland Answer choice A is incorrect; glucagon, from the alpha cells of the islets of Langerhans of the pancreas, raises blood glucose Answer choice D is incorrect; aldosterone is secreted by the adrenal cortex, and it increases sodium reabsorption in the kidneys Answer choice E is also known as ADH or vasopressin; its function is to increase water reabsorption in the collecting tubules of the kidneys 24 C The Hardy-Weinberg law states that gene ratios and allelic frequencies remain constant through the generations in a nonevolving population Four criteria must be met for this to occur: Random mating; a large population; no migration into or out of the population; and a lack of mutation If all four of these are met, the gene frequencies will remain constant Anytime all four of these are not met, the gene frequencies will change and evolution may occur 25 E The hypothalamus is involved in the regulation of a large number of basic human functions, including temperature regulation, sleep/wake cycles, water and salt balance, hunger, and many others It produces hormones such as vasopressin and oxytocin, which are stored in the posterior pituitary It also produces releasing factors that control the secretions of the anterior pituitary Answer choice A is incorrect because the medulla is involved in such basic functions as regulation of heart rate and breathing rate Answer choice B is incorrect because the pons contains tracts that connect the cerebrum to other parts of the brain, and it also works in conjunction with the medulla in controlling breathing rate Answer choice C is incorrect because the cerebrum is in charge of such functions as memory, conscious thought, voluntary motor activity, and the interpretation of sensation Answer choice D is incorrect because the pineal gland secretes the hormone melatonin, which is involved in the control of circadian rhythms and which also may be involved in sexual maturation 26 D Glucagon is secreted by a cells in the islets of Langerhans in the pancreas The function of glucagon is to increase blood glucose by causing the liver to change glycogen back into glucose, and to cause muscle cells to change glycogen to glucose and release it into the bloodstream It is the antagonist to choice A, insulin, which stimulates the opposite conversion of glucose to glycogen Answer choice B is incorrect because parathyroid hormone increases blood calcium by removing it from stored calcium in bone and other tissues Answer choice C is incorrect because pepsin is a proteolytic enzyme that works in the acidic environment of the stomach Answer choice E is incorrect because calcitonin lowers blood calcium by storing it in bone and other tissue 27 B The hypothalamus will release factors that will cause the anterior pituitary to produce the hormones FSH and LH FSH, or follicle stimulating hormone, will stimulate the ovary to produce mature ovarian follicles During the follicular KAPLAN _ 11 B I O L O G Y S U B J E C T T E S T stage, the ovary is also producing the hormone estrogen As the estrogen is released, FSH levels will drop and LH, or luteinizing hormone, levels will increase The drop in FSH and increase in LH will trigger the follicle to release the ovum This is known as ovulation The LH continues to affect the former follicle, which is now called the corpus luteum The corpus luteum secretes progesterone Answer choice B would occur first The secretion of estrogen by the ovary, under the influence of FSH during the follicular stage, will occur immediately before choice E, a decrease in FSH release by the pituitary This decrease of FSH is caused in part by high levels of estrogen The decrease in FSH, accompanied by an increase in LH, will cause choice A, rupture of the follicle, which is ovulation Following that, answer choice C, the corpus luteum will form As the corpus luteum matures, answer choice D, progesterone levels will increase 28 D The large intestine is primarily involved in water reabsorption Some salts and minerals are also reabsorbed with this water, and bacteria within the large intestine can also produce vitamin K Answer choice A is incorrect because the duodenum is the anterior section of the small intestine, which connects to the posterior end of the stomach Answer choice B is incorrect because the jejunum is the second section of the small intestine It connects to the duodenum on its anterior end and to the ileum on its posterior end Answer choice C is incorrect because the stomach is primarily a food-holding organ Some small amount of protein digestion occurs there Answer choice E is incorrect because the mouth does not absorb water, but it does chew and moisten food and convert a small amount of starch to maltose through the enzyme salivary amylase 29 E The pancreas is both an exocrine and endocrine organ The exocrine function is performed by the cells that secrete digestive enzymes such as amylase, lipase, and maltase, and bicarbonate into the small intestine via a series of ducts The endocrine function is performed by small glandular structures called the islets of Langerhans, which are composed of alpha, beta, and delta cells Alpha cells produce and secrete glucagon; beta cells produce and secrete insulin; delta cells produce and secrete somatostatin 30 C Continuous muscle contraction utilizes all the available oxygen, and causes the muscle fiber to depend on anaerobic respiration for energy NAD+ must be regenerated for glycolysis to continue in the absence of O2 This is accomplished by reducing pyruvate into lactic acid and only produces two ATP per glucose 31 E Viruses are simple, non-living organisms, which take on living characteristics when they infect a cell They contain either DNA or RNA and a protein coat in the form of a capsule Their genetic material is not in the form of a chromosome but is actually a complex of nucleic acids and proteins known as histone They must have a host cell in order to replicate, although this cell can be either a eukaryote or a prokaryote 32 D Bile is an emulsifying agent, which increases the surface area of fats allowing an increase in contact with the enzyme lipase, which breaks down fats It is not an enzyme as it does not catalyze a chemical change of fats The lipid molecules are still lipids, only smaller particles of lipids after interaction with bile Bile is made up of bile salts that are cholesterol derivatives, and pigments from the breakdown of hemoglobin Answer choice A is incorrect because hormones are chemical messengers that send signals to their target cells Answer choice B is incorrect because enzymes catalyze chemical reactions Answer choice C is incorrect because proteins are complex organic polymers of amino acids linked together by peptide bonds Answer choice E is incorrect because proteases are enzymes that digest proteins 12 _ KAPLAN _ B I O L O G Y S U B J E C T T E S T 33 D ATP and phosphocreatine are energy storage molecules located in the muscle fibers They release the energy utilized during contraction as actin and myosin filaments slide along one another Answer choice A is incorrect because lactic acid is a byproduct of anaerobic respiration, not an energy source Answer choice B is incorrect because lactose is a disaccharide known as milk sugar made up of glucose and galactose Answer choice C is incorrect because ADP is a low energy form of ATP Answer choice E is incorrect because cAMP is a second messenger found in cells that are target cells of peptide hormones 34 C Hyperthyroidism results in an excess of thyroxin and other thyroid hormones These hormones increase the basal metabolic rate and blood pressure Patients with hyperthyroidism are often characterized by sensitivity to heat, and nervousness Answer choices A, B, D, and E, hypothyroidism, on the other hand, is characterized by low metabolism, low heart rate, low body temperature, and diminished mental activity 35 B CO, like O2, is attracted to and stored on hemoglobin molecules It binds hemoglobin actually more strongly than O2, and is almost irreversibly bound by hemoglobin It is found in incompletely burned fuels, faulty space heaters, and barbecue grills used indoors CO is not irritating as it is odorless and colorless It does not form complexes in blood or affect the cytochrome chain It is a hemoglobin poison and does not affect the mitochondria or the sodium pump 36 B Mitochondria are the sites of aerobic respiration within the cell and hence the suppliers of energy Each mitochondrion is bound by an outer and an inner phospholipid bilayer membrane The outer membrane is smooth and acts as a sieve, allowing molecules through on the basis of size The area between the inner and outer membranes is known as the intermembrane space The inner membrane has many convolutions called cristae and a high protein content that includes the proteins of the electron transport chain The area bounded by the inner membrane is known as the mitochondrial matrix and is the site of many of the reactions in cell respiration Mitochondria are different from the other organelles in that they are semiautonomous; that is, they contain their own circular DNA and ribosomes, which enables them to produce some of their own proteins and to self-replicate by binary fission 37 D Metabolic waste products are the compounds that are released during enzymatic processes in cells The accumulation of waste products can kill the cell and the entire organism, so they must be cleared from the body Pyruvate is an intermediate of cellular respiration, and is either anaerobically converted into the waste product lactate or further metabolized into the wastes CO2 and H2O Pyruvate is not a waste product, so choice D is correct Choices A and C are incorrect because both are the waste products of aerobic respiration If CO2 is not removed, it can lead to acidosis of the blood, since CO2 can react with H2O to form carbonic acid CO2 is removed at the lungs Choice B is incorrect because lactate is the waste product of anaerobic respiration Lactate is eventually converted to pyruvate in the liver when O2 becomes available If it is not metabolized, it can lead to lactic acidosis (acidification of the blood) and death Choice E is incorrect because ammonia is the waste product of protein metabolism Ammonia is converted to the less toxic urea in the liver, and removed by the kidneys If ammonia is not converted and cleared, it can cause the blood to become alkaline, which is potentially fatal KAPLAN _ 13 B I O L O G Y S U B J E C T T E S T 38 C Blastulation begins when the morula develops a fluid-filled cavity called the blastocoel, which by the fourth day of human development will become a hollow sphere of cells called the blastula Choice A is incorrect because the zygote is the diploid (2N) cell that results from the fusion of two haploid (N) gametes Choice B is incorrect: The morula is the solid ball of cells that results from the early stages of cleavage in an embryo Choices D and E are incorrect The gastrula is the embryonic stage characterized by the presence of endoderm, ectoderm, the blastocoel and the archenteron The early gastrula is two-layered; later a third layer, the mesoderm, develops 39 A The electron transport chain (ETC) is a complex carrier mechanism that generates ATP through oxidative phosphorylation and it occurs in the inner mitochondrial membrane Choice B is incorrect because glycolysis is the oxidative breakdown of glucose into two molecules of pyruvate and it occurs in the cytoplasm Choice C is incorrect because the Krebs cycle occurs in the mitochondrial matrix The Krebs cycle is a cycle which begins when acetyl CoA combines with OAA to form citrate Then a complicated series of reactions follows which results in the release of CO2 and the regeneration of OAA Choice D is incorrect because fatty acid degradation occurs in microbodies called peroxisomes which beak down fat into smaller molecules to use as fuel Choice E is incorrect because ATP synthesis occurs in the matrix (Krebs cycle), inner mitochondrial membrane (ETC), and in the cytoplasm (glycolysis) 40 D ACh is inactivated in the synaptic cleft by the enzyme acetylcholinesterase after it has acted upon the postsynaptic membrane If chemical X denatures acetylcholinesterase, it will not be able to inactivate acetylcholine and prevent the continuous depolarization of the effector membrane 14 _ KAPLAN ... _ B I O L O G Y S U B J E C T T E S T Biology Subject Test Which of the following produces bile? A B C D E A B C D E spleen liver bone marrow... B I O L O G Y S U B J E C T T E S T BIOLOGY SUBJECT TEST ANSWER KEY D D 17 E 25 E 33 D C 10 D 18 D 26 D 34 C E 11 D 19 D 27 B 35 B D 12 C 20... NOT true? The sympathetic nervous system causes which of the following? A B C D E Small intestine Large intestine Gall bladder Liver Pancreas In the adult man, red blood cells are produced in the
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